THE BRAIN

Neurons found to aid myelin growth

Activating nerve cells in the brain appears to trigger the formation of another type of cell that is responsible for building the insulating sheaths that make neural communication possible, according to Stanford scientists.

When nerve cells fire, they prompt the production of oligodendrocytes, which make the protective sheaths called myelin, the scientists found. In their study, the researchers looked at mice that had been implanted with neurons that were programmed to activate in response to light waves. When the neurons "lit up," that set off the propagation of cells that create myelin.

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The study suggests that repeated activities - in other words, repeated activation of certain neurons and, in turn, increased myelin production - leads to the creation of stronger, more efficient communication paths between regions of the brain.

The research helps explain brain "plasticity," which involves the strengthening, and weakening, of neural connections based on activities deemed most important. The production of myelin, the scientists said, plays an important role in brain plasticity.

The study results were published online April 10 in the journal Science Express.

More in Health

COGNITION

Sleep problems linked to decline in older men

Older men who have certain sleeping problems - including frequent episodes of waking up in the middle of the night and not being able to fall back to sleep - may be at increased risk for suffering cognitive decline in the following years, according to scientists from California Pacific Medical Center and UCSF.

The researchers studied 2,822 men ages 67 or older, all of whom had no cognitive problems. The men wore wristbands to track their sleeping habits over a five-day period.

Participants who experienced fragmented sleep and low sleep efficiency were 40 to 50 percent more likely to lose some cognitive function over the next three to four years, compared with men who didn't have those sleep problems.

The total amount of time spent sleeping and self-reported sleep quality were not associated with cognitive decline, the researchers found.

The research was published April 1 in the journal Sleep.

- Erin Allday

OVARIAN CANCER

Irregular menses tied to greater cancer risk

Women with irregular menstrual periods had twice the risk of ovarian cancer compared with those with regular cycles, according to new research from the Public Health Institute in Berkeley.

That risk increased to nearly threefold in women who had both irregular cycles and a family history of ovarian cancer involving a first-degree relative such as a mother or sister.

The study was based on medical data collected from more than 14,000 women at Kaiser Permanente in Oakland who had given birth between 1959 and 1967. The patients were followed for more than 50 years as part of the Child Health and Development Studies, a Kaiser study of pregnancy and child development.

Infertility and the use of fertility drugs or contraceptives were ruled out as an explanation of the study findings.

While previous studies have suggested longer cycles or less frequent ovulation may protect the ovary, this new research did not support that. The irregularities reported by women in the study included those with cycles lasting longer than 35 days or who did not release an egg during ovulation.

CANCER EVALUATION

Cheaper genetic testing can aid in treatment

Running a relatively quick and cheap multiple-gene panel test on patients at high risk of certain cancers may help doctors make better medical recommendations for those patients, according to Stanford researchers.

While whole-genome sequencing is available, the process tends to be both time-consuming and expensive. The use of gene panels - tests involving just a few select genes that tend to have mutations associated with certain cancers - have become an increasingly popular option.

In the Stanford study, researchers assessed the sequences of 42 genes known to be associated with the development of breast cancer and potentially many other cancers.

They ran the sequencing on samples of blood from nearly 200 women who underwent testing for BRCA 1 and BRCA 2 mutations, the most common and well-known mutations associated with breast and ovarian cancers.

Among the 141 women without those mutations, 14 had genetic mutations in the 42-gene panel, raising their cancer risk enough that doctors could recommend a change in care, such as increased screenings and preventive measures.

The study was published Monday in the Journal of Clinical Oncology.

- Victoria Colliver

ALZHEIMER'S DISEASE

Women at higher risk from genetic variant

A gene variant that some scientists already believed is a key risk factor for Alzheimer's disease turns out to be even more dangerous for women than men, according to researchers at Stanford School of Medicine.

ApoE4, one of three variants in the ApoE gene, a recipe for a protein that shuttles fatty substances throughout the body, may help scientists understand Alzheimer's more.

Researchers analyzed clinical assessments of 5,000 people with normal test results and 2,200 people who had initially showed signs of mild cognitive impairment. The chances of Alzheimer's increased in both groups when the ApoE4 gene variant was detected. But among those who initially tested normal, the increased risk was only marginal for men, but women had close to twice the likelihood of progressing to mild cognitive impairment or Alzheimer's disease, their recent study found.

AGRICULTURAL WORKERS

Study finds illnesses, accidents underreported

More than three-quarters of incidents of agricultural workers getting hurt or sickened on the job go unreported by federal agencies, according to a new UC Davis study.

Without accurate data, farmers can't fix the problems to make the nation's food suppliers safer and healthier, according to the report, published in the Annals of Epidemiology this month.

"Whatever anyone might have assumed about gaps in government statistics for agriculture, our study shows that the problem is actually about three times bigger than previously suspected," said J. Paul Leigh, professor of public health sciences and the lead investigator in the study.

The problem for the discrepancy is government's focus on mid- to large-size farming enterprises, which only account for 50 percent of employment in agricultural industries, according to the study.

Leigh and other researchers came to their conclusion by combining data for 2011 on nonfatal work-related injuries and illness from myriad federal agencies and found that the government had missed 73.7 percent of crop farm cases and 81.9 percent of animal farm cases, for an average of 77.6 percent for all agriculture.

"Our analysis used a combination of datasets along with reliable ratios to arrive at a more reasonable and accurate assessment than any single government resource can provide," Leigh said. "Agriculture is a major driver of economic wealth as well as one of the most hazardous employment environments in the nation. It could be an even more powerful economic force if we accurately counted and addressed the causes of harm to workers and farmers."

- Stacy Finz

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